/* ------------------------------------------------------------------------
 *
 * geqo_ox2.cpp
 *
 *	 order crossover [OX] routines;
 *	 OX2 operator according to Syswerda
 *	 (The Genetic Algorithms Handbook, ed L Davis)
 *
 * src/gausskernel/optimizer/geqo/geqo_ox2.cpp
 *
 * -------------------------------------------------------------------------
 */
/* contributed by:
   =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
   *  Martin Utesch				 * Institute of Automatic Control	   *
   =							 = University of Mining and Technology =
   *  utesch@aut.tu-freiberg.de  * Freiberg, Germany				   *
   =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
 */
/* the ox algorithm is adopted from Genitor : */
/*************************************************************/
/* 															 */
/* 	Copyright (c) 1990										 */
/* 	Darrell L. Whitley										 */
/* 	Computer Science Department								 */
/* 	Colorado State University								 */
/* 															 */
/* 	Permission is hereby granted to copy all or any part of  */
/* 	this program for free distribution.   The author's name  */
/* 	and this copyright notice must be included in any copy.  */
/* 															 */
/*************************************************************/

#include "postgres.h"
#include "knl/knl_variable.h"
#include "optimizer/geqo_random.h"
#include "optimizer/geqo_recombination.h"

/* ox2
 *
 *	 position crossover
 */
void ox2(PlannerInfo* root, Gene* tour1, Gene* tour2, Gene* offspring, int num_gene, City* city_table)
{
    int k, j, count, pos, select, num_positions;

    /* initialize city table */
    for (k = 1; k <= num_gene; k++) {
        city_table[k].used = 0;
        city_table[k - 1].select_list = -1;
    }

    /* determine the number of positions to be inherited from tour1  */
    num_positions = geqo_randint(root, 2 * num_gene / 3, num_gene / 3);

    /* make a list of selected cities */
    for (k = 0; k < num_positions; k++) {
        pos = geqo_randint(root, num_gene - 1, 0);
        city_table[pos].select_list = (int)tour1[pos];
        city_table[(int)tour1[pos]].used = 1; /* mark used */
    }

    count = 0;
    k = 0;

    /* consolidate the select list to adjacent positions */
    while (count < num_positions) {
        if (city_table[k].select_list == -1) {
            j = k + 1;
            while ((city_table[j].select_list == -1) && (j < num_gene))
                j++;

            city_table[k].select_list = city_table[j].select_list;
            city_table[j].select_list = -1;
            count++;
        } else
            count++;
        k++;
    }

    select = 0;

    for (k = 0; k < num_gene; k++) {
        if (city_table[(int)tour2[k]].used) {
            offspring[k] = (Gene)city_table[select].select_list;
            select++; /* next city in  the select list   */
        } else
            /* city isn't used yet, so inherit from tour2 */
            offspring[k] = tour2[k];
    }
}
